The invention relates to improvements to a horizontal continuous substrate treatment plant for the treatment, for example coating, of slab-shaped substrates, for example glass panels, wherein the substrates, with or without substrate mounts, lying on a conveying device, i.e. in a horizontal orientation, are conveyed through a plant chamber delimited by chamber walls or an arrangement of a plurality of plant chambers arranged behind one another of a substrate treatment plant, wherein the substrates are subjected to the effect of at least one substrate treatment device, such as, for example, coating devices, etching devices, etc. The substrate treatment, on the one hand, often takes place under a pressure which is lower than the atmospheric pressure (process vacuum), and, on the other hand, also often in a selected gas or gas mixture which is often introduced in a controlled manner (process atmosphere).
In contrast to what are referred to as batch substrate treatment plants, in continuous substrate treatment plants generally at least in each case a plant chamber, which is configured as a lock chamber, is located upstream and downstream of the plant chamber or an arrangement of a plurality of plant chambers arranged behind one another, which may be configured, for example, as process chambers, pump chambers, transfer chambers, etc., and a conveying device is arranged inside the substrate treatment plant such that said conveying device extends through the two lock chambers and through all other plant chambers arranged in between.
As a result, substrates can be moved in a conveying direction through the substrate treatment plant in that they are introduced into the substrate treatment plant by means of a first lock chamber, conveyed through the entire arrangement of plant chambers arranged behind one another by means of the conveying device, and are evacuated from the substrate treatment plant by means of a second lock chamber. Here, the substrates in at least one process chamber are also moved past a substrate treatment device arranged in said process chamber and thereby subjected to the desired substrate treatment
For the treatment of slab-shaped substrates, conveying devices have proven successful which comprise a plurality of rotatably mounted, cylindrical conveying rollers which are arranged transversely to the conveying direction of the substrates, the uppermost generatrices of said conveying rollers defining a horizontal conveying plane for the substrates, and at least some of said conveying rollers being drivable. In the event that the desired substrate treatment takes place under elevated process temperatures, for example 400, 600 or 800° C., it has proven successful to produce the conveying rollers from heat-resistant materials, for example ceramics, or to coat them with a heat-resistant material.
The invention relates to a conveying roller for a conveying device of a horizontal continuous substrate treatment plant, in particular for carrying out coating and/or etching processes on flat (slab-shaped) substrates such as architectural glass, solar cells and so on, and to a conveying device having such conveying rollers. Such processes generally take place at subatmospheric pressure, where appropriate in the presence of a process gas, for example an inert gas or a reactive gas, and in some cases under high temperatures, for example 600 or 800° C.
Depending on the particular application, the conveying rollers can be manufactured from metallic materials, for example stainless steel or aluminum, or from nonmetallic materials, for example industrial ceramic such as aluminum oxide, silicon dioxide and so on. In the case of conveying rollers made of ceramic materials, it is further known to provide the ends, on which the conveying rollers are rotatably mounted, with end caps made of metallic materials which serve to mount, center and transmit the force of the conveying rollers. Here, the connection between the roller body and the end cap must satisfy two conditions; firstly, the end cap must be seated concentrically on the end of the roller body in order to ensure the concentric running of the conveying roller, and, secondly, the connection between the two must be such that the torque required to drive the conveying roller can be transmitted.
It is known to produce the connection between the end cap and the roller body by means of adhesive bonding; however, this solution has obvious disadvantages with regard to the temperature resistance of the connecting point between ceramic and metal and by virtue of the fact that an adhesive connection is nonreleasable. Particularly in coating plants in which the conveying rollers are exposed to contamination during the operation, there is moreover the risk that chemical cleaning processes adversely affect the adhesives such that the end caps can become released from the roller body.
In EP 0 393 292 A1 and EP 0 388 206 B1, slotted sleeves have been proposed for mounting ceramic roller bodies, which sleeves are braced from outside against the roller body by means of clamping screws. However, highly accurate centering is not possible therewith.
In U.S. Pat. No. 5,906,567 it is, by contrast, proposed to connect the end caps to the roller body by means for producing a rotationally fixed connection and additionally by means for centering. This solution is very complicated and therefore involves high costs.
DE 30 06 114 C3 discloses a solution in which a radial clamping ring which is intended to effect the transmission of torque is arranged between the roller body and the end cap. However, this approach is problematic because the radial clamping ring can naturally exert a force only on one of the two components to be connected and thus now tight limits are set for the size of the torque which can be transmitted.
Various further approaches are known from EP 0 789 829 B1, for example using bimetallic lamellae or wedges and elastic means interacting therewith or pins arranged transversely to the longitudinal axis of the roller.
WO 2010/094716 A1 has proposed a conveying roller for the vacuum treatment of substrates, which comprises a ceramic roller body with two ends and two metallic end caps with in each case a receiving opening, wherein each end of the roller body is arranged in a receiving opening of an end cap and is connected in a rotationally fixed manner to the end cap, and at least one helical spring or a clamping pin parallel to the axis of symmetry (longitudinal axis) of the roller body is arranged between the end of the roller body and the receiving opening of the end cap.